Elastic stranded laminate with adhesive bonds and method of manufacture

ABSTRACT

A laminated article having elastic strands or filaments contained therein for providing elasticity to the article, are provided. The particular adhesive pattern bonds the relatively inelastic nonwoven layers to the more elastic continuous filaments in a pattern that allows adhesive-to-adhesive, adhesive-to-nonwoven layer, and adhesive-to-elastic filament bonding.

FIELD OF THE INVENTION

[0001] This invention relates to laminated composite nonwoven articlesand, in particular, to a process for producing an elastic and/orrelatively inelastic nonwoven laminate that may be used for a variety ofapplications such as in diapers, athletic bandages or other productsthat require a degree of elasticity.

BACKGROUND OF THE INVENTION

[0002] Composites of elastic and nonelastic materials are commonly madeby combining elastics and nonelastics in a lamination process to providethe entire composite with a degree of stetchability or elasticity. Theseelasticized composites may then be used as the elastic components forvarious articles disposable personal care products such as, for example,diapers, pads, medical bandages, and the like.

[0003] Generally, when forming such composites, a nonelastic material(or at least a less elastic material) is joined by bonding to an elasticmaterial (or at least a more elastic material) while the elasticmaterial or sheet is in a stretched condition. When the tension on themore elastic material is released, the less elastic component of thecombination is allowed to gather in the spaces between the bondingsites. The resulting composite elastic material is stretchable to theextent that the less elastic material gathered between the bondlocations allows the more elastic sheet to elongate. Examples of thesetypes of composite laminate articles and materials are set forth in U.S.Pat. Nos. 4,720,415 and 5,385,775, each of which is incorporated byreference herein.

[0004] In some stretchable laminate articles, elastic strands ofcontinuous filaments are bonded to relatively inelastic sheet materialswhile the elastic strands are in a stretched condition. Such elasticcontinuous filaments may, in certain articles, be sandwiched between twoor more relatively inelastic sheets. The relatively inelastic sheets mayinclude nonwoven webs formed by meltblowing or spunbonding variouspolymers. Examples of such laminates are shown in U.S. Pat. No.5,385,775 to Wright, which is incorporated herein in its entirety byreference thereto.

[0005] As shown in Wright, elastic continuous filaments may be extrudedonto a horizontally moving sheet of material. The continuous filamentsare extruded from above the horizontal plane of sheet material anddirectly onto the material for bonding thereto.

[0006] In other exemplary laminates, after bonding the elasticcontinuous filaments to the sheet material, which will often berelatively inelastic, the bonded elastic continuous filament/inelasticnonwoven sheet material will then be stretched and another relativelyThe forces that are holding the elastic continuous filaments in astretched condition are then released to gather the inelastic nonwovensheet(s) between the sheet bonding points. In use, the product may bestretched to expand and ungather the inelastic sheet(s), but will, uponrelease, return to the shortened, gathered state.

[0007] Other lamination processes have also been developed for forming astretchable laminate product from elastic and inelastic materials. Forexample, U.S. Pat. No. 4,910,064 to Sabee shows an apparatus formanufacturing an integral filamentary web comprising continuousfilaments and meltblown fibers. A multiple number of continuousfilaments are spun in curtain-like form, one side of which will havemolten meltblown fibers deposited thereon and self-bonded to fix thecontinuous filaments in a controlled alignment. The process involvesdrawing continuous filaments either before, during, or after thedeposition of the meltblown fibers in order to molecularly orient thecontinuous filaments. After stabilizing elastic continuous filaments bybonding to the meltblown fibers and relaxing the filaments, the elasticfilaments and the web contract to form buckles, curls, or kinks in thenon-elastic molecularly oriented permanently lengthened continuousfilaments. The patent further describes the bonding of a second opposingmeltblown web to the opposite side of the continuous filaments after themeltblown fiber/continuous filament composite is at least partiallydrawn to provide some degree of molecular orientation.

[0008] In addition, U.S. Pat. Nos. 5,200,246 and 5,219,633, also toSabee, show a vertically-oriented process and apparatus for producing afabric that combines elongatable continuous filaments with fibrousmeltblown webs for interlocking the continuous filaments in anintegrated, fibrous, continuous filament matrix. An extruder providesmolten elastomeric continuous filaments which are cooled, solidified,and stretched as they are drawn from the meltblowing nozzle bycounter-rotating temperature-controlled pull rolls. The solidifiedcontinuous filaments are then subsequently pulled into the nip of a pairof temperature-controlled deposition rolls whereat two opposingmeltblown gas-fiber streams or sprays are simultaneously and turbulentlyintermingled with each other and between the tensioned continuouselastomeric filaments. Passing the fabric between higher velocity drawrolls may then further stretch the composite fabric.

[0009] In the manufacture of such laminates, adhesives have been used tohold elastic strands or filaments in place, thereby bonding the elasticstrands or filaments to nonwoven facing materials. U.S. Pat. No.4,880,420 to Pomparelli discloses a method of applying adhesive to bondelastic strands to a fabric by using a sinusoidal-shaped line ofadhesive. In Pomparelli, a relatively thick portion of adhesive isapplied in a line along one or more elastic filaments in a directiongenerally parallel to the elastic filaments. However, the line ofadhesive disclosed in Pomparelli does not intersect itself at any point.Instead, the sinusoidal adhesive line intersects a predetermined numberof the same elastic strands several times as the line winds its wayacross the strands.

[0010] One problem in the manufacture of elasticized articles is thatusing adhesives to bond elastic strands to a nonwoven sometimes causesthe article to be stiff, rather than soft. In diapers, for example,excessive adhesive results in a stiff or inflexible diaper product thatis undesirable to consumers. Also, if the adhesive is not applied in apreferred pattern, and is not efficiently utilized, it cannot reachoptimum performance to provide the greatest bonding strength for eachgram of adhesive applied to the article. Thus, a challenge in makingproducts of this type is to find ways to use less adhesive, but stillimpart sufficient bonding strength to securely fix elastic filamentsinto a nonwoven.

SUMMARY OF THE INVENTION

[0011] The present invention provides new methods for and patterns ofapplying adhesive materials to elastic strand-containing laminatearticles. The articles in which the present invention may be utilizedinclude various articles that require portions of elasticity such asdiapers, tampons, and absorbent garments. Such articles will typicallyinclude one or more nonwoven layers and a plurality of elastic filamentsor strands bonded to the nonwoven layer(s) to provide the desired degreeof elasticity. Typically, an adhesive material is used to bond thestrands to the nonwoven layer(s). In the bonding arrangement of thepresent invention, the adhesive material is applied in lines thatintersect the elastic filaments to form a bonding network comprised ofadhesive-to-elastic bonds, adhesive-to-facing bonds, andadhesive-to-adhesive bonds.

[0012] The adhesive patterns utilized in the present invention willtypically be lines that lie perpendicular or nearly perpendicular to theelastic components. Although true 90-degree bond angles may bedesirable, the average or mean bond angle may be as small as 50 degrees,and will typically be approximately 60 degrees. A greater bond anglewill generally result in increased bonding strength between thecontinuous filaments and the nonwoven layer to which the filaments arebonded.

[0013] In the bonding arrangement of the present invention, theadhesive-to-elastic bonds are formed at the points where the lines ofadhesive and elastic material join or intersect and theadhesive-to-adhesive bonds are formed at the points where the lines ofadhesive intersect or join themselves.

[0014] One particular embodiment in which the present invention may beutilized is an absorbent article (garment) or infant diaper wherein lessthan 0.6 grams of adhesive is applied per article to bond the elasticstrands of the articles to the contiguous nonwoven facing layers. Thisresults in a product that is generally free from unnecessary stiffnesswhile retaining a solid and stable bonding of elastic filaments tononwoven facing material.

[0015] In one aspect of the invention, a process of manufacturing anabsorbent laminated article is utilized. The process comprises providinga nonwoven layer and spraying an adhesive upon the surface of thenonwoven layer, wherein the adhesive is applied to the nonwoven layer ina non-random pattern that is capable of providing predetermined strengthcharacteristics to the laminate structure. Further, the process includesproviding a plurality of substantially parallel elastic filamentsadjacent the nonwoven layer, the elastic filaments being extruded from adie in molten form and then cooled. Finally, the process includespressing the (1) nonwoven layer, (2) elastic filaments, and (3) adhesivetogether in a nip to form a laminated article.

[0016] Other objects, advantages and applications of the presentinvention will be made clear by the following detailed description ofembodiments of the invention and the accompanying drawings whereinreference numerals refer to like or equivalent structures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a perspective view of one particular apparatus forlaminating together continuous filaments and nonwoven facing(s);

[0018]FIG. 2A shows a cross-section of a laminated absorbent article ofthe invention wherein an adhesive spray has been applied onto thesurface of one nonwoven facing;

[0019]FIG. 2B depicts a cross-section of a laminated absorbent articleof the invention wherein an adhesive spray has been applied onto bothopposing nonwoven facings;

[0020]FIG. 3A shows a bonding pattern in which the adhesive has beenapplied to the elastic filaments with attenuation in thecross-direction;

[0021]FIG. 3B shows an adhesive bonding spray or scrim pattern;

[0022]FIG. 3C shows another adhesive bonding spray or scrim pattern;

[0023]FIG. 3D illustrates conceptually the bond angle in a scrim bondingpattern of this invention;

[0024]FIG. 4 shows the bonding pattern and method of calculating thenumber of bonds per unit length on elastic strands or filaments inaccordance with the present invention;

[0025]FIG. 5A illustrates a swirled type of adhesive bonding pattern;

[0026]FIG. 5B shows a randomized adhesive bonding pattern having amajority of adhesive lines in a perpendicular orientation to the elasticfilaments;

[0027]FIG. 5C is a graphical representation of an adhesive laydownpattern with attenuation of adhesive lines in the cross-machinedirection;

[0028]FIG. 5D shows a “chain-link fence” type pattern of adhesive bondedto the elastic filaments; and

[0029]FIG. 6 is a schematic view of another particular apparatus forlaminating together continuous filaments and nonwoven facing(s).

DEFINITIONS

[0030] The term “continuous filaments”, as used herein, refers tostrands of continuously formed polymeric filaments. Such filaments willtypically be formed by extruding molten material through a die headhaving a certain type and arrangement of capillary holes therein.

[0031] The term “elastic” or “elasticized”, as used herein, refers to amaterial which, upon application of a biasing force, is stretchable,which is elongatable to at least about 60 percent (i.e., to a stretched,biased length which is at least about 160 percent of its relaxedunbiased length), and which will recover at least 55 percent of itselongation upon release of the stretching force. A hypothetical exampleof an elastic material would be a one (1) inch sample of a materialwhich is elongatable to at least 1.60 inches and which, when released,will recover to a length of not more than 1.27 inches. Many elasticmaterials may be elongated by more than 60 percent (i.e., more than 160percent of their relaxed length). For example, some elastic material maybe elongated 100 percent or more, and many of these will recover tosubstantially their initial relaxed length such as, for example, within105 percent of their original relaxed length upon release of thestretching force.

[0032] As used herein, the term “polymer” generally includes, but is notlimited to, homopolymers, copolymers, such as, for example, block,graft, random and alternating copolymers, terpolymers, etc. and blendsand modifications thereof. Furthermore, the term “polymer” includes allpossible geometrical configurations of the material, such as isotactic,syndiotactic and random symmetries.

[0033] The term “composite nonwoven fabric”, “composite nonwoven”,“laminate”, or “nonwoven laminate”, as used herein, unless otherwisedefined, refers to a material having at least one elastic materialjoined to at least one sheet material. In most embodiments suchlaminates or composite fabric will have a gatherable layer which isbonded to an elastic layer or material so that the gatherable layer maybe gathered between bonding locations. As set forth herein, thecomposite elastic laminate may be stretched to the extent that thegatherable material gathered between the bond locations allows theelastic material to elongate. This type of composite elastic laminate isdisclosed, for example, in U.S. Pat. No. 4,720,415 to Vander Wielen etal., which is incorporated herein in its entirety by reference thereto.

[0034] As used herein, the term “nonwoven web” refers to a web having astructure of individual fibers or threads that are interlaid, but not inan identifiable, repeating manner. Nonwoven webs have been, in the past,formed by a variety of processes such as, for example, meltblowingprocesses, spunbonding processes and bonded carded web processes.

[0035] As used herein, the term “meltblown fibers” means fibers formedby extruding a molten thermoplastic material through a plurality offine, usually circular, die capillaries as molten thermoplastic materialor filaments into a high velocity gas (e.g. air) stream which attenuatesthe filaments of molten thermoplastic material to reduce their diameter,which may be to microfiber diameter. Thereafter, the meltblown fibersare carried by the high velocity gas stream and are deposited on acollecting surface to form a web of randomly disbursed meltblown fibers.Such a process is disclosed, for example, U.S. Pat. No. 3,849,241 toButin, which is incorporated herein in its entirety by referencethereto.

[0036] As used herein, the term “spunbonded fibers” refers to smalldiameter fibers formed by extruding a molten thermoplastic material asfilaments from a plurality of fine, usually circular, capillaries of aspinerette with the diameter of the extruded filaments then beingrapidly reduced as by, for example, eductive stretching or otherwell-known spun-bonding mechanisms. The production of spun-bondednonwoven webs is illustrated in patents such as, for example, U.S. Pat.No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschneret al. The disclosures of these patents are incorporated herein in theirentireties by reference thereto.

[0037] As used herein, “scrim” refers generally to a fabric or nonwovenweb of material which may be elastic or inelastic, and having a machinedirection oriented along the path of manufacture and a cross-direction.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Reference now will be made to the embodiments of the invention,one or more examples of which are set forth below. Each example isprovided by way of explanation of the invention, not as a limitation ofthe invention. In fact, it will be apparent to those skilled in the artthat various modifications and variations can be made in this inventionwithout departing from the scope or spirit of the invention. Forinstance, features illustrated or described as part of one embodimentcan be used on another embodiment to yield a still further embodiment.Thus, it is intended that the present invention cover such modificationsand variations as come within the scope of the appended claims and theirequivalents. Other objects, features and aspects of the presentinvention are disclosed in or are obvious from the following detaileddescription. It is to be understood by one of ordinary skill in the artthat the present discussion is a description of exemplary embodimentsonly, and is not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstructions.

[0039] As mentioned above, elastic stranded laminates are used in avariety of personal care product applications such as waistbands, legcuffs, side panels, and the like in which a tight, yet comfortable,elastic fit is needed. Products requiring such an elastic-strandedlaminate include disposable diapers, disposable training pants, andadult-care briefs. Soft, flexible facings made from materials such aspolymer films and nonwovens surround the strands of elastomeric polymersin these laminates. Adhesives are commonly used to bond the facings tothe strands, and the facings to the facings.

[0040] One particular means of applying adhesives to the laminatesutilizes meltblown spray technology. In this technology, meltblowingequipment presents the adhesive to the laminate layer in a randomfibrous configuration. Multiple adhesive-to-elastic strand bonds perunit length of elastic are formed, along with multiple facing to facingadhesive bonds per unit area. In general, strong, flexible adhesivebonds are required to maintain the flexibility and integrity of thelaminate in use. If the adhesive-to-elastic bonds are too few in numberor are too weak, then the elastic tension properties of the laminatewill be compromised as the tension of the elastic strands will break theadhesive joints. The common remedy in prior art processes for remedyingthis condition is to increase the number of bonding sites by eitherincreasing the meltspray air pressure, or by slowing the laminationspeed. As the meltspray air pressure is increased, the resultingadhesive fiber size is reduced in these known processes, creating weakerbonds. Increasing the amount of adhesive used per unit area to createlarger adhesive filaments usually repairs this, but this usuallyincreases the cost of the laminate. Lowering the lamination speeddecreases machine productivity, but negatively impacts product cost.

[0041]FIGS. 2A and 2B illustrate the use of such meltspray webs. In FIG.2A, a cross-section of a laminated article produced with the typicalmeltspray adhesive is shown. A laminated article 26 is shown as having afirst nonwoven facing 27 and second nonwoven facing 28. Melt-sprayadhesive layer 29 is applied between the nonwoven facings, andcontinuous elastic filaments 30 are seen in cross-section. FIG. 2Bdepicts a cross-section of a laminated article 32 wherein melt-sprayadhesive 29 has been applied on both nonwoven facings 27 and 28.

[0042] The present invention, however, employs an elastic strandedlaminate where the number of bond sites per length elastic strand areprescribed or predetermined, and the adhesive-to-elastic strand jointsare generally perpendicular in orientation to provide enhanced strength.This allows the laminate to be made at minimal cost by optimizing theadhesive and elastomer content to match the product needs.

[0043] The adhesives are applied according to the present invention in acontinuous, wave-shaped pattern that intersects the elastic strands in apredominantly perpendicular fashion. The bonding of the continuousadhesive filaments to the elastic strands at their intersections is alsocontrolled to a known number per unit elastic strand length so thatpredictable and controllable laminate properties are achieved. Byencapsulating high-strength adhesive to elastic strand bonds with aperpendicular orientation and optimizing the number of bonds per unitelastic strand length, the elastic strand laminates of the presentinvention can be produced with only a minimal amount of adhesive andelastomer. In addition, the adhesives are applied in some embodiments ofthe present invention to obtain both adhesive-to-elastic bonds andadhesive-to-adhesive bonds as well as adhesive-to-facing bonds, with theadhesive-to-adhesive bonding contributing to the strengthcharacteristics of the present invention.

[0044] Although the invention will be described and depicted in thecontext of a continuous filament/nonwoven laminate forming apparatusthat is in a vertical orientation, it is to be understood that variousother apparatuses may be employed in forming the laminates. Thevertically-oriented laminate forming apparatus is depicted in FIG. 1.This apparatus includes an extruder 15 that forms continuous filaments14 and then guides the continuous filaments through a series of rollersuntil the filaments are placed into position for bonding to one or morenonwoven facings. In other embodiments, such as in FIG. 6, the series ofrollers may be eliminated. Various apparatuses may be employed in thepresent invention and are described more specifically in co-pendingapplication owned by the present assignee and bearing Ser. No.60/204,307 and filed on May 15, 2001, as a Provisional Application (andlater filed as a Utility application) with the title: “Method andApparatus for Producing Laminated Articles”. That application (both theProvisional application and the corresponding Utility application) isincorporated herein in its entirety by reference thereto.

[0045] Various types of compositions and various processing conditionsmay be utilized to form the elastic continuous filaments. For example, aKraton®-brand elastic polymer may be fed into an extruder where thepolymer is melted at a controlled temperature of between about 260° and460° F., and in certain instances at about 385° F. In other embodiments,depending on the particular polymer employed, the melt temperature maybe approximately 470° F. to 480° F. The polymer is then extruded througha predetermined number of apertures in a die head in a generallydownward direction into separate continuous filaments at a pressure ofapproximately 300 to 4000 psi (typically from about 1500 to about 2000psi).

[0046] One particular class of polymers that may be utilized in thepresent process is the Kraton® G series of polymers distributed by ShellChemical Company (now available from Kraton Products U.S.-LLC). VariousKraton® G polymers may be utilized.

[0047] In one embodiment, the blend used to form the elastomericcontinuous filaments as well as the facings include, for example, fromabout 40 to about 80 percent by weight elastomeric polymer, from about 5to about 40 percent polyolefin, and from about 5 to about 40 percentresin tackifier. For example, a particular composition may include, byweight, about 61 to about 65 percent KRATON® G-1657 (in one instance,about 63 percent), about 17 to about 23 percent polyethylene NA 601-04wax (in one instance, about 20 percent), and about 15 to about 20percent REGALREZ™ 1126 (in one instance, about 17 percent). The G-1657is, in particular, a styrene-ethyl butylene-styrene (S-EB-S) triblockbase rubber polymer.

[0048] In another embodiment, a polymer blend consisting ofapproximately 85% A-B-A′-B′ tetrablock base rubber polymer (sold asG1730 by Kraton Products) and 15% polyethylene NA601 wax may beemployed. In this particular instance, the A and A′ in the rubberpolymer may be thermoplastic blocks containing a styrene moiety and Band B′ may be elastomeric polymer blocks consisting ofpoly(ethylene-propylene).

[0049] In an additional embodiment, a polymer blend consisting ofapproximately 80% A-B-A′-B′ tetrablock base rubber polymer, 7%polyethylene NA601 wax, and 13% REGALREZ™ 1126 tackifier may be used. Asabove, the A and A′ in the rubber polymer may be thermoplastic blockscontaining a styrene moiety and B and B′ may be elastomeric polymerblocks consisting of poly(ethylene-propylene).

[0050] In another embodiment, a polymer blend consisting ofapproximately 70% A-B-A′-B′ tetrablock base rubber polymer and 30%polyethylene NA601 wax may be utilized. As above, the A and A′ in therubber polymer may be thermoplastic blocks containing a styrene moietyand B and B′ may be elastomeric polymer blocks consisting ofpoly(ethylene-propylene).

[0051] These various compositions may be utilized to form both thecontinuous filaments and the spunbond outer facing(s). However, thepresent invention is not limited to these or any particular polymer ormaterial from which to form the continuous filaments. For example,various materials, including the following, may be used: polypropylene,polyethylene, polyesters, polyethylene terephthalate, polybutane,polymethyidentene, ethylenepropylene co-polymers, polyamides, tetrablockpolymers, styrenic block copolymers, polyhexamethylene adipamide,poly-(oc-caproamide), polyhexamethylenesebacamide, polyvinyls,polystyrene, polyurethanes, thermoplastic polymers,polytrifluorochloroethylene, ethylene vinyl acetate polymers,polyetheresters, polyurethane, polyurethane elastomerics, polyamideelastomerics, polyamides, viscoelastic hot melt pressure sensitiveadhesives, cotton, rayon, hemp and nylon. In addition, such materialsmay be utilized to extrude single-constituent, bi-constituent, andbi-component filaments within the scope of the presently describedinvention.

[0052] Other exemplary elastomeric materials that may be used includepolyurethane elastomeric materials such as those available under thetrademark ESTANE from B. F. Goodrich & Co., polyamide elastomericmaterials such as those available under the trademark PEBAX from theRilsan Company, and polyester elastomeric materials such as thoseavailable under trade designation HYTREL from E. I. DuPont De Nemours &Company.

[0053] However, the invention is not limited to only such elastomericmaterials. For example, various latent elastic materials such as theArnitel-brand polymers may be utilized to provide the necessaryelasticity characteristics to the continuous filaments.

[0054] Various extruder dies may be utilized in forming the continuousfilaments. In addition, various processing steps and parameters may beemployed, depending on the characteristics desired in the final product.For example, the die of the extruder that forms the continuous filamentsmay be positioned with respect to the first roller so that thecontinuous filaments meet this first roller at a predetermined angle.The angle between the die exit of the extruder and the vertical axis (orthe horizontal axis of the first roller, depending on which angle ismeasured) may be as little as a few degrees or as much as 90°. Anglessuch as about 20°, about 35°, or about 45° away from vertical may beutilized.

[0055] The rollers are positioned and operated so as to cause thecontinuous filaments to be stretched as they vertically flow through thebank of rollers. Each successive roller turns in a direction opposite tothe immediately preceding roller so that the strands of continuousfilaments are handed off from roller to roller. In addition, the speedof each successive roller may be varied from the preceding roller so asto obtain the desired stretching and elongation characteristics.

[0056] The number of separate rollers used to convey the continuousfilaments to the bonding location may vary depending on the particularattributes desired in the final product. In one particular embodiment,at least four rollers—a first chilled (or positioning) roller, a secondchilled roller, a third unchilled roller, and a fourth unchilledroller—may be utilized. In certain embodiments, the rollers may beplasma coated to provide good release properties. In other embodiments,the rollers may additionally be grooved or channeled to ensure that theextruded continuous filaments maintain a proper separation betweenindividual filaments as the filaments pass over the surface of the rollsand flow through the system. In some embodiments, smooth rolls maybeused for one or all of the rolls. After passing through the chillrollers (either the series or the one or two chill rollers shown in FIG.6) and becoming stretched, the continuous filaments are then conveyedinto a position so that a sheet material may be bonded to the continuousfilaments. In other embodiments, the number of rollers in the series maybe substantially reduced. In fact, only one or two chilled rollers maybe necessary to achieve the products of the present invention.

[0057] In certain embodiments, this sheet material will be less elasticthan the continuous filaments. The sheet material may be variousnonwoven webs such as meltblown webs, spunbond webs, or carded webs,various woven webs, or a film material. Certain enhanced properties andproduction efficiencies, however, arise from the use of polymericspunbond nonwoven webs. In one particular embodiment, a polypropylenespunbond facing having a basis weight of approximately 0.4 ounces persquare yard (“osy”) may be employed.

[0058] The materials utilized to form the continuous filaments may alsobe utilized in forming the outer facings of the presently describedlaminate. In particular, various webs may be utilized that are formedfrom elastomeric or nonelastomeric fibers. Various polyester elasticmaterials are, for example, disclosed in U.S. Pat. No. 4,741,949 toMorman et al., which is incorporated herein in its entirety by referencethereto. Other useful elastomeric polymers also include, for example,elastic copolymers of ethylene and at least one vinyl monomer such as,for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids,and esters of such monocarboxylic acids. The elastic copolymers andformation of elastomeric fibers from these elastic copolymers aredisclosed in, for example, U.S. Pat. No. 4,803,117, which is alsoincorporated herein in its entirety by reference thereto.

[0059] The facing(s) of the present invention may be a mixture ofelastic and nonelastic fibers or particulates. For example, U.S. Pat.No. 4,209,563 is incorporated herein in its entirety by referencethereto and describes the process by which elastomeric andnonelastomeric fibers are commingled to form a single coherent web ofrandomly dispersed fibers. Another example of such an elastic compositeweb is shown in U.S. Pat. No. 4,741,949, which is also incorporatedherein in its entirety by reference thereto wherein an elastic nonwovenmaterial is described as including a mixture of meltblown thermoplasticfibers and other materials. The fibers and other materials may becombined in the forming gas stream in which the fibers are borne so thatan intimate entangled commingling of fibers and other materials, e.g.,wood pulp, staple fibers or particulates such as, for example, activatedcharcoal, clays, starches, or hydrocolloid (hydrogel) particulates,occurs prior to collection of the fibers upon a collecting device toform a coherent web of randomly dispersed fibers.

[0060] Various processing aids may also be added to the elastomericpolymers utilized in the present invention. For example, a polyolefinmay be blended with the elastomeric polymer (e.g., the A-B-A elastomericblock copolymer) to improve the processability of the composition. Thepolyolefin should be one which, when so blended and subjected to anappropriate combination of elevated pressure and elevated temperatureconditions, is extrudable in blended form with the elastomeric polymer.Useful blending polyolefin materials include, for example, polyethylene,polypropylene and polybutene, including ethylene copolymers, propylenecopolymers and butene copolymers. A particularly useful polyethylene maybe obtained from the U.S.I. Chemical Company under the trade designationPetrothene NA 601 (also referred to herein as PE NA 601 or polyethyleneNA 601). Two or more of the polyolefins may be utilized. Extrudableblends of elastomeric polymers and polyolefins are disclosed in, forexample, U.S. Pat. No. 4,663,220, which is incorporated herein in itsentirety by reference thereto.

[0061] The elastomeric materials that are utilized to form themelt-spray adhesive and/or the elastomeric filaments may have sufficienttackiness to enhance the bonding strength of the laminate by allowing adegree of autogenous bonding. For example, the elastomeric polymeritself may be tacky when formed into fibers and/or filaments or,alternatively, a compatible tackifying resin may be added to theextrudable elastomeric compositions described above to provide tackifiedelastomeric fibers and/or filaments that autogenously bond. Variousknown tackifying resins and tackified extrudable elastomericcompositions may be employed, such as those described in U.S. Pat. No.4,787,699, which is incorporated herein in its entirety by referencethereto.

[0062] Any tackifier resin can be used that is compatible with theelastomeric polymer and can withstand the extrusion processingconditions. If the elastomeric polymer (e.g., A-B-A elastomeric blockcopolymer) is blended with processing aids such as, for example,polyolefins or extending oils, the tackifier resin should also becompatible with those processing aids. Generally, hydrogenatedhydrocarbon resins exhibit enhanced temperature stability and, thus, maybe desirable tackifiers. REGALREZ™ hydrocarbon and ARKON™ seriestackifiers are examples of hydrogenated hydrocarbon resins. ZONATAK™ 501lite is an example of a terpene hydrocarbon. REGALREZ™ hydrocarbonresins are available from Hercules Incorporated. ARKON™ series resinsare available from Arakawa Chemical (U.S.A.) Incorporated. Of course,the present invention is not limited to use of such tackifying resins,and other tackifying resins that are compatible with the othercomponents of the composition and that can withstand the processingconditions may also be used.

[0063] The adhesive employed to bond the continuous filaments to thesheet(s) will be applied to the laminate after the continuous filamentshave been positioned on the sheet(s). The adhesive lines may be appliedby using a stationary spray head capable of forming the predeterminedpattern or by using moving nozzle(s) that are designed to follow thepredetermined pattern path required for the adhesive line. In addition,one or two, or more, spray heads may be utilized. Various equipment forapplying the adhesive lines of the present invention may be utilized andthe invention is not limited to any particular apparatus.

[0064] In general, the adhesive bonds anchoring the elastic strands inthe present laminate are regulated per unit area by the applicationsystem such that key properties such as stretch and elongation can becontrolled to precisely match product performance needs.

[0065] This invention allows for the optimization of the adhesive,elastomer, and facings in the laminate, thus providing a preferred matchof laminate properties and laminate cost. Laminate properties that canbe more precisely adjusted with this invention include the softness ordrapability of the material—a minimal amount of adhesive can be utilizedto provide a less rigid structure. Further, the laminate tensioncharacteristics can be better tailored to product requirements usingthis invention because the adhesive bonds can be prescribed and/orpredetermined along the elastic strands. Thus, a minimal number of theadhesive bonds can be used in certain embodiments to allow moreflexibility in the elastomer. Laminate elongation and retractionproperties also may be designed to meet product needs by controlling thenumber of adhesive bonding sites. The level of strand slippage in thelaminate (i.e., the amount that the strands slide between the facingsamong bonding sites) may be regulated to meet product needs by alsoprescribing the number of adhesive bonding sites. The amount of laminatebulk may be also be modulated since the retraction and resultingbuckling of the facings can be controlled due in part to the ability toregulate the number of adhesive bond sites along the elastic strands.

[0066] Adhesives are typically employed in laminates of the typeprovided by the present invention because the facing materials andelastomeric components are constructed of polymers that often do notreadily bond to each other. The use of an external adhesive-bondingagent, however, rectifies this problem. In addition, the elastomerutilize to form the continuous filaments may be pre-compounded with aselective adhesive component that readily migrates to the surface of theelastic, thus making the continuous filaments perform more like asheath-core filament. This migration to the surface can provide theneeded bonding agent while preserving the elasticity of the elastomer.

[0067] Various types of adhesives may be employed in the presentinvention, including those having elastomeric properties such asKraton®-containing adhesives that are available from the FindleyAdhesives Company (known also as Bostik Findley). Among the variousadhesives that may be employed are Findley-brand H2096 and Findley-brandH2525A.

[0068] In the absence of autogenous bonding, the adhesives may be usedto bond the facings to the strands, and the facings to the facings. Theparticular adhesive system utilized may result in a composite fabriccomposite with improved texture and drape. Various adhesives asdiscussed herein or that are otherwise available may be employed in thepresent system. For some products, such as a coformed stretch-bondedlaminate wet wipe, the use of a high melt flow ratemetallocene-catalyzed polyethylene elastomeric resin that has low tackmay be advantageously utilized to provide improved texture and drape.Because of its low melting temperature, such a resin is capable offorming a physical interlock when thermally bonded. That is, the resincan penetrate into porous facings.

[0069] Dow Chemical Company resins having a relatively low density(between about 0.86 and about 0.88 g/cm³) may be efficiently utilized inthe adhesive system of the present invention. Other Dow resins havinglower melt flow rates have also demonstrated the ability to create aphysical interlock under thermal bonding conditions. The resin alsocould be blended with a tackifier or a lower melt flow elastomer toproduce an optimized adhesive system. High melt flow elastomers may besuitable as alternate adhesive systems in the VFL process describedherein.

[0070] The system employs nip rolls to apply pressure to theadhesive-coating facing and the continuous filaments to result in thenecessary lamination. The outer facing is bonded together with thecontinuous filaments at a fairly high surface pressure, which may bebetween about 20 and about 300 pounds per linear inch (“pli”). A typicalbonding pressure may be about 50 pli or about 100 pli.

[0071] The bonder, or nip roll, (sometimes referred to as “laminator”)section of the laminating apparatus performs the primary stretching onthe continuous filaments. The speed ratio of the bonder or nip rollsrelative to the chilled rolls can be varied, and in most cases isbetween about 2:1 and 8:1, and in some approximately 4:1 to 6:1.

[0072] In certain embodiments, one or more additional facings may bebonded to the other unattached surface of the stretched continuousfilaments so as to achieve a stretchable article wherein the continuousfilaments are sandwiched between at least two outer facings. Variousbonding techniques may be utilized to form this two-layer/continuousfilament laminate. The adhesive line techniques of the present inventionmay be employed or known melt-spray techniques may be employed,depending on the particular characteristics desired in the finalproduct. The requirement of the present invention is that at least oneof the facings is bonded to the continuous filaments utilizing thedescribed predetermined patterns.

[0073] Several patents describe various spray apparatuses and methodsthat may be utilized in supplying the meltspray adhesive to the outerfacing(s) or, when desired, to the elastic strands themselves. Forexample, the following United States patents assigned to Illinois ToolWorks, Inc. (“ITW”) are directed to various means of spraying ormeltblowing fiberized hot melt adhesive onto a substrate: U.S. Pat. Nos.5,882,573; 5,902,540; 5,904,298. These patents are incorporated hereinin their entireties by reference thereto. The types of adhesive sprayequipment disclosed in the aforementioned patents are generallyefficient in applying the adhesive onto the nonwoven facings in theprocess of this invention. In particular, ITW-brand Dynatec sprayequipment, which is capable of applying about 3 gsm of adhesive at a runrate of about 1100 fpm, has been used successfully in the melt-sprayadhesive applications contemplated by the present inventive process.

[0074] After bonding of the facing(s) to the continuous filaments toform a spunbond/elastomeric continuous filament/spunbond laminate, thelaminate is then allowed to relax and contract to an unstretched or lessstretched, condition. The laminate is then wound onto a take-up roll viaa surface driven winder. The speed ratio of the winder relative to thebonder rollers results in relaxation of the stretched continuousfilaments and a retraction of the laminate into a gathered state as thelaminate is wound onto the roll. The contraction of the continuousfilaments results in a gathered, stretchable laminate article where theouter facing(s) is gathered between the bonding points.

[0075] The overall basis weight of the laminate can vary, but in someapplications is between about 2 and about 4 ounces per square yard(“osy”). In one particular embodiment, the basis weight is between about2.85 and about 3.2 osy.

[0076]FIG. 1 illustrates an exemplary vertically-configured apparatus 11for forming the continuous filament/spunbond laminates of the presentinvention. An extruder 15 is mounted for extruding continuous moltenfilaments 14 downward from a die at a canted angle onto chilledpositioning roller 12. Chilled positioning roller 12 ensures properalignment through the remainder of the system as it spreads thefilaments. As the filaments travel over the surface of chilledpositioning roller 12, they are cooled and solidified as they traveltowards and over the chilled surface of first chilled roller 13. Thefilaments then travel downward in an “s-shaped” progression, in thisparticular embodiment, to second roller 16 and then across the surfaceof third roller 17, fourth roller 18 and into the nip formed by niproller 19 and nip roller 20.

[0077] The continuous filaments may be combined at the nip with varioustypes of facings. In the embodiment depicted in FIG. 1, a firstnon-woven spunbond facing 22 and second non-woven spunbond facing 24 arecombined on opposing surfaces of the continuous filaments to form abonded laminate 25. In some embodiments, only one facing may be used,and in other embodiments it is possible to combine the elasticcontinuous filaments with three, four, or more layers of facingmaterial.

[0078] Bonding of the facings to the continuous filaments typicallyoccurs by utilizing an adhesive as described above. The adhesive may beapplied with a stationary spray head 23 that delivers adhesive to thesurface of at least one of the non-woven spunbond facings in apredetermined adhesive line pattern or may be applied with a movingadhesive nozzle (not shown) that is guided on the apparatus to followthe predetermined bonding pattern. As shown in FIG. 1, stationary sprayhead 23 may be positioned on the back side of the point where facing 22will meet with continuous filaments 14. Nip rollers 19 and 20 may bealigned so that adhesive 50 can be applied to the continuous filaments14 and facing 22 as they are brought together into the laminating nipsection. A second adhesive-applying spray head or nozzle (not shown) maybe employed in some embodiments to provide an adhesive line to the otherfacing 24 to allow bonding to the other surface of the continuousfilaments.

[0079] Alternatively, the adhesive may be applied to the surface of thenonwoven sheet material prior to the sheet material being placed intocontact with the continuous filaments. In this embodiment, the facingcarries the adhesive lines until the continuous filaments are broughtinto adhering contact at the adhesive bonding points.

[0080] In another embodiment of the present system, the aforementionedseries of s-wrap rollers may be eliminated as shown in FIG. 6. In thisFigure, as in FIG. 1, an exemplary apparatus is depicted in order tocarry out the above-described process. The VFL system 111 is verticallyconfigured. An extruder 115 is mounted for extruding continuous moltenfilaments 114 downward from a die at a canted angle onto chilledpositioning roller 112. Chilled positioning roller 112 ensures properalignment through the remainder of the system as it spreads thefilaments. As the filaments travel over the surface of chilledpositioning roller 112, they are cooled and solidified as they traveltowards and over the chilled surface of chilled roller 113. As in otherembodiments, the filaments then travel downward toward the laminatorsection of the system comprising a nip formed by nip roller 119 and niproller 120, but in this instance, do so without the need for the seriesof s-wrap rollers described above. The continuous filaments in thisembodiment may also be combined at the nip with various types offacings. In the embodiment depicted in FIG. 6, a first non-wovenspunbond facing 122 and a second non-woven spunbond facing 124 arecombined on opposing surfaces of the continuous filaments to form abonded laminate 125. The spunbond facings 122 and 124 are provided tothe nip by first outer facing roll 127 and second outer facing roll 128.

[0081] Bonding of the facings to the continuous filaments isaccomplished in this embodiment by the use of two spray-type adhesiveapplicators. A spray head 123 delivers adhesive to the surface of atleast one of the non-woven spunbond facings 122 prior to compression andlamination at the nip; and a second spray head 152 applies adhesive tothe other non-woven spunbond facing 124.

[0082] Take-up roll 21 (shown in FIG. 1) may be employed for receivingand winding the bonded spunbond/continuous filament/spunbond laminate 25for storage.

[0083]FIG. 3A illustrates one exemplary adhesive pattern useful in thepresent invention in which the adhesive has been applied to the elasticfilaments with attenuation of the adhesive lines in the cross-machinedirection. Pattern 35 includes adhesive lines 36 and elastic filaments30. This pattern utilizes only adhesive-to-elastic bonds.

[0084]FIG. 3B illustrates another exemplary scrim pattern 38 havingadhesive lines 39 applied to elastic strands 30 and the adhesive lines39 themselves. This pattern takes advantage of additional bonding at theadhesive-to-adhesive points. In fact, the adhesive overlaps itself in agenerally perpendicular fashion to provide greater bonding strength. Thebond angle is very high, approaching 90° at the intersection between theadhesive and the elastic filaments.

[0085]FIG. 3C illustrates another scrim pattern 41 having adhesive lines42 and continuous elastic strands 30. This embodiment utilizesadhesive-to-adhesive bonding, but not to the extent of the patternillustrated in FIG. 3B.

[0086]FIG. 3D illustrates the relatively high bond angle that may beemployed in products produced according to the present invention. Inparticular, lay down angle 44 is shown as the angle formed by theadhesive line 48 and the elastic strand 30. Adhesive/elastic angle 46and adhesive/elastic angle 45 are shown as being less than 90°.

[0087]FIG. 4 utilizes an exemplary bonding pattern to conceptuallyillustrate the measurement for determining the number of bonds per unitlength on elastic strands or filaments. By employing specified bonds perunit length, various desirable characteristics can be obtained.

[0088]FIG. 5A shows another exemplary bonding pattern employingadhesive-to-adhesive bonding wherein a swirled type of configuration isemployed. FIG. 5B illustrates a more randomized pattern wherein a largepercentage of adhesive lines are in a perpendicular, or almostperpendicular, orientation to the elastic filaments. FIG. 5C is anotherexemplary embodiment of a bonding pattern having no adhesive-to-adhesivebonds, but numerous adhesive-to-elastic strand bonds.

[0089]FIG. 5D illustrates another exemplary bonding pattern that hasboth adhesive-to-adhesive and adhesive-to-elastic strand bonds. Theconfiguration shown in FIG. 5D is similar to the design of a chain-linkfence and provides excellent bonding strength.

[0090] The present invention may be better understood by reference tothe Examples below. However, it is to be understood that the inventionis not limited thereto.

EXAMPLE 1

[0091] In this Example, an ITW-brand nozzle having 17 holes per inch wasemployed for creating and analyzing various spray patterncharacteristics. In particular, an adhesive polymer melt (Findley-brandH2525A) was employed at various fiber diameters, basis weights, andnozzle pressures to determine percent coverage and orientation (i.e.,“anisotropy”). Orientation is the tangent of the average orientation ofthe spray pattern. In Table 1, when the orientation is less than 1.000,then orientation of the adhesive spray was in the machine direction andwhen the orientation is more than 1.000, then orientation of theadhesive spray was in the cross-machine direction. When the orientationhas a value of 1.00, then the orientation is 45°, meaning that theorientation is neither dominant in the machine direction nor in thecross-machine direction. In addition, coverage is the ratio of adhesivepresence to no adhesive presence. “%COV” equals 100(standarddeviation/mean of the percent-area histogram), with the smaller %coverage exhibiting better overlap of the adhesive to form theadhesive-to-adhesive bonds. “Formation” is the coefficient of variationfor formation. The fiber diameter is the average fiber size inmicro-milliliters. TABLE 1 Fiber Basis Diameter, Orientation Formation,% Coverage, Weight PSI mean (μm) (Tan θ) Coverage % Area 3 20 85.4 1.2033.5 14.2 3 40 53.9 1.18 23.6 16.9 4 40 79.9 1.16 29.5 20.8 3 60 65.11.13 16.5 23.7 3 80 55.6 0.89 13.6 23.1

EXAMPLE2

[0092] In this Example, an ITW-brand nozzle having 5 holes per inch wasemployed for creating and analyzing various spray patterncharacteristics. In particular, an adhesive polymer melt (Findley-brandH2525A) was employed as described above at various fiber diameters,basis weights, and nozzle pressures. TABLE 2 Fiber Basis Diameter,Orientation Formation, % Coverage, Weight PSI mean (μm) (Tan θ) Coverage% Area 3 16 139 1.18 41.9 11.9 3 30 120 1.37 34.3 12.2 4 16 152 1.4927.6 14.6

EXAMPLE 3

[0093] In this Example, an ITW-brand nozzle having 14 holes per inch wasemployed for creating and analyzing various spray patterncharacteristics. In particular, an adhesive polymer melt consisting ofFindley-brand H2096 was employed at various fiber diameters, nozzlepressures, and basis weights as above to determine percent coverage andorientation. The temperature of the adhesive was 360° F. and thetemperature of the air was 420° F. The height of the nozzle above thelaydown materials was 1.25 inches. As with Table 1, when the orientationis less than 1.000, then orientation of the adhesive spray was in themachine direction and when the orientation is more than 1.000, thenorientation of the adhesive spray was in the cross-machine direction. Inaddition, “%COV” equals 100(standard deviation/mean of the percent-areahistogram), with the smaller % coverage exhibiting better overlap of theadhesive to form the adhesive-to-adhesive bonds.

[0094] The lines speeds of the various samples were varied. The firstfour samples employed a line speed of 500 feet per minute; the nextthree samples employed a line speed of 1000 feet per minute; and thelast seven samples employed a line speed of 1500 feet per minute. TABLE3 Fiber Basis Diameter, Orientation Formation, % Coverage, Weight PSImean (μm) (Tan θ) Coverage % Area 1.5 11 128 1.095 48.1 15.6 1.5 17 1161.19 37.7 19.6 3.0 11 153 1.439 33.5 24.8 3.0 17 135 1.488 25.7 24.8 1.517 134 1.259 37.1 14 3.0 17 157 1.12 37.5 17.6 3.0 17 158 1.425 48.118.2 1.5 17 139 0.807 29.4 25.6 1.5 17 129 0.869 36.7 24.8 1.5 23 1390.996 45.2 14.2 1.5 23 135 1.118 39.3 13.8 3.0 17 160 0.913 34.3 34.43.0 17 163 0.944 29.2 33.2 3.0 23 160 1.007 17.8 14.6

[0095] It is understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstructions. The invention is shown by example in the appended claims.

What is claimed is:
 1. An laminated fabric article comprising: (a) afacing layer; (b) a plurality of elastic filaments adjacent to a surfaceof the facing layer; and (c) an adhesive component, wherein the adhesivecomponent is applied to the surface of the nonwoven layer in adhesivelines, the adhesive lines intersecting both the elastic filaments andthemselves to form a bonding network comprised of adhesive-to-elasticbonds, adhesive-to-facing layer, and adhesive-to-adhesive bonds.
 2. Thelaminated fabric article of claim 1 wherein said adhesive linesintersect said elastic filaments at an angle of greater than 45° andless than 90°.
 3. The laminated fabric article of claim 1 wherein saidadhesive lines intersect said elastic filaments at an angle of betweenabout 50° and about 90°.
 4. The laminated fabric article of claim 1wherein said adhesive lines intersect said elastic filaments at an angleof between about 60° and about 90°.
 5. The laminated fabric article ofclaim 1 wherein said adhesive lines intersect said elastic filaments atan angle of about 60°.
 6. The laminated fabric article of claim 1comprising an additional facing.
 7. The laminated fabric article ofclaim 1 wherein said adhesive component is about 3 to about 5 gsm inweight.
 8. The laminated fabric article of claim 1 wherein said articlehas a basis weight of between about 2 to about 4 osy.
 9. The laminatedfabric article of claim 1 wherein said facing layer comprises aspunbonded nonwoven web.
 10. The laminated fabric article of claim 6wherein said additional facing comprises a spunbonded nonwoven web. 11.The laminated fabric article of claim 6 wherein said continuousfilaments and said adhesive component are between said facing layers.12. A method of manufacturing a laminated fabric article comprising: (a)providing a facing layer; (b) providing a plurality of elastic filamentsadjacent to a surface of the facing layer; and (c) applying an adhesivecomponent to bond said elastic filaments to said facing layer inadhesive lines that intersect both the elastic filaments and themselvesto form a bonding network comprised of adhesive-to-elastic bonds,adhesive-to-facing layer, and adhesive-to-adhesive bonds.
 13. The methodof claim 12 further comprising the steps of: providing a second facinglayer and applying an adhesive component to said second facing layer tobond said elastic filaments to said facing layer in adhesive lines thatintersect both the elastic filaments and themselves to form a bondingnetwork comprised of adhesive-to-elastic bonds, adhesive-to-facinglayer, and adhesive-to-adhesive bonds.